This is a propeller i designed for a summer internship i did where i built a small pvc pipe submarine and everyone made different propeller designs to print out and test in the water.you might have to widen the hole in the center just a bit with a drill or something to fit over the shaft of a regular dc motor that you might find in an RC car but other than that it will work just fine in the water. If you still dont know then the diameter of the center hole is .05 inches and the whole propeller is 2.5 inches long.